Growth hormone (GH), which is secreted from the pituitary gland, stimulates growth of all tissues of the body that are capable of growing. In addition, growth hormone is known to have the following basic effects on the metabolic processes of the body:
1. Increased rate of protein synthesis in substantially all cells of the body;
2. Decreased rate of carbohydrate utilization in cells of the body; and
3. Increased mobilization of free fatty acids and use of fatty acids for energy.
Deficiency in growth hormone results in a variety of medical disorders. In children, it causes dwarfism. In adults, the consequences of acquired GH deficiency include profound reduction in lean body mass and concomitant increase in total body fat, particularly in the truncal region. Decreased skeletal and cardiac muscle mass and muscle strength lead to a significant reduction in exercise capacity. Bone density is also reduced. Administration of exogenous growth hormone has been shown to reverse many of the metabolic changes. Additional benefits of therapy have included reduction in LDL cholesterol and improved psychological well-being.
In cases where increased levels of growth hormone were desired, the problem was generally solved by providing exogenous growth hormone or by administering an agent which stimulated growth hormone production and/or release. In either case the peptidyl nature of the compound necessitated that it be administered by injection. Initially the source of growth hormone was the extraction of the pituitary glands of cadavers. This resulted in an expensive product, and carried with it the risk that a disease associated with the source of the pituitary gland could be transmitted to the recipient of the growth hormone (e.g., Jacob-Creutzfeld disease). Recently, recombinant growth hormone has become available which, while no longer carrying any risk of disease transmission, is still a very expensive product which must be given by injection or by a nasal spray.
Most GH deficiencies are caused by defects in GH release, not primary defects in pituitary synthesis of GH. Therefore, an alternative strategy for normalizing serum GH levels is by stimulating its release from somatotrophs. Increasing GH secretion can be achieved by stimulating or inhibiting various neurotransmitter systems in the brain and hypothalamus. As a result, the development of synthetic growth hormone-releasing agents to stimulate pituitary GH secretion are being pursued, and may have several advantages over expensive and inconvenient GH replacement therapy. By acting along physiologic regulatory pathways, the most desirable agents would stimulate pulsatile GH secretion, and excessive levels of GH that have been associated with the undesirable side effects of exogenous GH administration would be avoided by virtue of intact negative feedback loops.
Physiologic and pharmacologic stimulators of GH secretion include arginine, L-3,4-dihydroxyphenylalanine (L-DOPA), glucagon, vasopressin, and insulin induced hypoglycemia, as well as activities such as sleep and exercise, indirectly cause growth hormone to be released from the pituitary by acting in some fashion on the hypothalamus perhaps either to decrease somatostatin secretion or to increase the secretion of the known secretagogue growth hormone releasing factor (GHRF) or an unknown endogenous growth hormone-releasing hormone or all of these.
Other compounds have been developed which stimulate the release of endogenous growth hormone such as analogous peptidyl compounds related to GRF or the peptides of U.S. Pat. No. 4,411,890. These peptides, while considerably smaller than growth hormones are still susceptible to various proteases. As with most peptides, their potential for oral bioavailability is low. WO 94/13696 refers to certain spiropiperidines and homologues which promote release of growth hormone.
The compounds of WO 94/11012 and WO 94/13696 are reported to be useful in the treatment of osteoporosis in combination with parathyroid hormone or a bisphosphonate.
In one aspect, this invention relates to a method of treating insulin resistant conditions such as Non-insulin Dependent Diabetes Mellitus (NIDDM) and reduced glycemic control associated with obesity and aging in a mammal in need thereof which comprises administering to said mammal an effective amount of a compound of the formula I, defined below, or a pharmaceutically acceptable salt thereof.
This invention is directed to the use of growth hormone secretagogues specifically growth hormone releasing peptides (GHRP) or GHRP mimetics of formula I, defined below, to improve glycemic control. Agents that increase growth hormone (GH) levels would not be expected to have this effect since it is widely recognized that GH is diabetogenic in animals and in humans. In acromegalics, glucose utilization and suppression of hepatic glucose production are impaired (see Hansen, I., et al., Am J Physiol, 250:E269 (1986)). In this disease of GH excess, impaired glucose handling and hyperinsulinemia have been reversed by pituitary surgery or chemotherapy which reduced GH levels (see Levin S. R., et al., Am J Med, 57:526 (1974), Feek, C. M., et al., J Clin Endocrinol 22:532 (1981)). Furthermore, administration of GH to older subjects caused hyperglycemia, glucose intolerance and hyperinsulinemia in numerous studies (see Aloia, J. F., et al., J Clin Endocrinol Metab, 43:992 (1976); Binnerts et al., J Clin Endocrinol Metab, 67:1312 (1988); Marcus, R., et al., J Clin Endocrinol Metab, 70:519 (1990)). Therefore, GH therapy is contra-indicated for individuals with diabetes or those at risk for diabetes.
Obesity is a major risk factor for diabetes, and a large fraction of NIDDM patients are obese. Both conditions are characterized by elevated circulating insulin levels and suppressed GH levels. GH treatment of GH-deficient adults (Jorgensen, J. O. L., et al., Lancet 1:1221 (1989)), obese women (Richelsen, B., et al., Am J Physiol, 266:E211 (1994)) and elderly men (Rudman, D., et al, Horm Res 36 (Suppl 1):73 (1991)) has been shown to produce increases in lean body, hepatic and muscle mass while decreasing fat mass. Thus, GH therapy for obesity would seem attractive except for the diabetogenic effects of GH.
An alternative to exogenous GH administration is therapy that stimulates endogenous GH secretion. It has been shown that a substantial pituitary reserve of GH is present in pituitary-intact GH-deficient patients and the elderly so that decreased serum GH levels are due to hyposecretion.
Hyposecretion of GH in several clinical settings (obesity, aging, glucocorticoid suppression) is relatively resistant to stimulation by GHRH (Gertz, B. J., et al., J Clin Endocrinol Metab, 79:745 (1994); Arvat, E., et al., J Clin Endocrinol Metab, 79:1440 (1994); Maccario, M., et al., Metabolism, 44:134 (1995)). In contrast, administration of a GHRP or combined administration of GHRH and a GHRP in these patients can elicit a robust GH response (Aloi, J. A., et al., J Clin Endocrinol Metab, 79:943; (1994)). Single dose studies of GHRPs have demonstrated the absence of an acute effect on circulating insulin or glucose levels. Insulin and glucose have generally not been monitored in chronic studies except to document the absence of unfavorable changes (Jacks, T., et al., J Endocrinol. 143:399 (1993)).
Prior to the present invention, the use of GHRPs or GHRP mimetics to improve glycemic control has not specifically been explored. The method of treating insulin resistance in a mammal comprising the administration of a compound of formula I is practiced preferentially in patients who have a functional hypothalamic-pituitary axis capable of GH secretory responses to GHRPs and who are diabetics (Type I or Type II), or are insulin resistant, or who show impaired glucose tolerance.
In another aspect, this invention is directed to methods for the treatment or prevention of congestive heart failure, obesity and frailty associated with aging, in a mammal in need thereof, which comprises administering to said mammal simultaneously, sequentially in any order or as a combination a functional somatostatin antagonist such as an alpha-2 adrenergic agonist, for example clonidine, xylazine or medetomidine, and a compound of formula I, defined below. In another aspect, this invention provides methods for accelerating bone fracture repair and wound healing, attenuating protein catabolic response after a major operation, and reducing cachexia and protein loss due to chronic illness in a mammal in need thereof, which comprises administering to said mammal simultaneously, sequentially in any order or as a combination an alpha-2 adrenergic agonist, such as clonidine, xylazine or medetomidine and a compound of formula I, defined below. Clonidine, which is disclosed in U.S. Pat. No. 3,202,660 the disclosure of which is hereby incorporated by reference, xylazine, which is disclosed in U.S. Pat. No. 3,235,550 the disclosure of which is hereby incorporated by reference and medetomidine, which is disclosed in U.S. Pat. No. 4,544,664 the disclosure of which is hereby incorporated by reference. It has been shown that alpha-2 adrenergic agonists cause release of endogenous growth hormone in human and canine subjects (Cella et al., Life Sciences (1984), 34:447-454; Hampshire J, Altszuler N. American Journal of Veterinary Research (1981), 42:6, 1073-1076; Valcavi et al., Clinical Endocrinology (1988), 29:309-316; Morrison et al., American Journal of Veterinary Research (1990), 51:1, 65-70;), and that the co-administration of an alpha-2 adrenergic agonist with growth hormone-releasing factor restores defective growth hormone secretion in aged dogs (Arce et al., Brain Research (1990), 537:359-362; Cella et. al., Neuroendocrinology (1993), 57:432-438).
In yet another aspect, this invention provides a process for the synthesis of a compound of the formula Z 
where the process is described below.
Further, this invention is directed to processes for preparing certain intermediates, shown below, which are useful in the synthesis of the compound of formula Z.
The compounds of formula I utilized in the present invention and the compound of formula Z are disclosed and claimed in co-pending PCT Application Number PCT/IB 96/01353 filed Dec. 4, 1996, which is assigned to the assignee hereof, wherein said compounds are disclosed as having activity as growth hormone secretagogues and which increase the level of endogenous growth hormone.
The compounds utilized in methods of this invention have the formula I, 
or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof,
wherein
e is 0 or 1;
n and w are each independently 0, 1 or 2;
provided that w and n cannot both be 0 at the same time;
Y is oxygen or sulfur;
R1 is hydrogen, xe2x80x94CN, xe2x80x94(CH2)qN(X6)C(O)X6, xe2x80x94(CH2)qN(X6)C(O)(CH2)txe2x80x94A1, xe2x80x94(CH2)qN(X6)SO2(CH2)txe2x80x94A1, xe2x80x94(CH2)qN(X6)SO2X6, xe2x80x94(CH2)qN(X6)C(O)N(X6)(CH2)txe2x80x94A1, xe2x80x94(CH2)qN(X6)C(O)N(X6)(X6), xe2x80x94(CH2)qC(O)N(X6)(X6), xe2x80x94(CH2)qC(O)N(X6)(CH2)txe2x80x94A1, xe2x80x94(CH2)qC(O)OX6, xe2x80x94(CH2)qC(O)O(CH2)txe2x80x94A1, xe2x80x94(CH2)qOX6, xe2x80x94(CH2)qOC(O)X6, xe2x80x94(CH2)qOC(O)(CH2)txe2x80x94A1, xe2x80x94(CH2)qOC(O)N(X6)(CH2)txe2x80x94A1, xe2x80x94(CH2)qOC(O)N(X6)(X6), xe2x80x94(CH2)qC(O)X6, xe2x80x94(CH2)qC(O)(CH2)txe2x80x94A1, xe2x80x94(CH2)qN(X6)C(O)OX6, xe2x80x94(CH2)qN(X6)SO2N(X6)(X6), xe2x80x94(CH2)qS(O)mX6, xe2x80x94(CH2)qS(O)m(CH2)txe2x80x94A1, xe2x80x94(C1-C10)alkyl, xe2x80x94(CH2)txe2x80x94A1, xe2x80x94(CH2)qxe2x80x94(C3-C7)cycloalkyl, xe2x80x94(CH2)qxe2x80x94Y1xe2x80x94(C1-C6)alkyl, xe2x80x94(CH2)qY1xe2x80x94(CH2)txe2x80x94A1 or xe2x80x94(CH2)qxe2x80x94Y1xe2x80x94(CH2)txe2x80x94(C3-C7)cycloalkyl;
where the alkyl and cycloalkyl groups in the definition of R1 are optionally substituted with (C1-C4)alkyl, hydroxyl, (C1-C4)alkoxy, carboxyl, xe2x80x94CONH2, xe2x80x94S(O)m(C1-C6)alkyl, xe2x80x94CO2(C1-C4)alkyl ester, 1H-tetrazol-5-yl or 1, 2 or 3 fluoro;
Y1 is O, S(O)m, xe2x80x94C(O)NX6xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, xe2x80x94Cxe2x89xa1Cxe2x80x94, xe2x80x94N(X6)C(O)xe2x80x94, xe2x80x94C(O)NX6xe2x80x94, xe2x80x94C(O)Oxe2x80x94, xe2x80x94OC(O)N(X6)xe2x80x94 or xe2x80x94OC(O)xe2x80x94;
q is 0, 1, 2, 3 or 4;
t is 0, 1, 2 or 3;
said (CH2)q group and (CH2)t group may each be optionally substituted with hydroxyl, (C1-C4)alkoxy, carboxyl, xe2x80x94CONH2, xe2x80x94S(O)m(C1-C6)alkyl, xe2x80x94CO2(C1-C4)alkyl ester, 1H-tetrazol-5-yl, 1, 2 or 3 fluoro, or 1 or 2 (C1-C4)alkyl;
R2 is hydrogen, (C1-C8)alkyl, xe2x80x94(C0-C3)alkyl-(C3-C8)cycloalkyl, xe2x80x94(C1-C4)alkyl-A1 or A1; where the alkyl groups and the cycloalkyl groups in the definition of R2 are optionally substituted with hydroxyl, xe2x80x94C(O)OX6, xe2x80x94C(O)N(X6)(X6), xe2x80x94N(X6)(X6), xe2x80x94S(O)m(C1-C6)alkyl, xe2x80x94C(O)A1, xe2x80x94C(O)(X6), CF3, CN or 1, 2 or 3 halogen;
R3is A1, (C1-C10)alkyl, xe2x80x94(C1-C6)alkyl-A1, xe2x80x94(C1-C6)alkyl-(C3-C7)cycloalkyl, xe2x80x94(C1-C5)alkyl-X1xe2x80x94(C1-C5)alkyl, xe2x80x94(C1-C5)alkyl-X1xe2x80x94(C0-C5)alkyl-A1 or xe2x80x94(C1-C5)alkyl-X1xe2x80x94(C1-C5)alkyl-(C3-C7)cycloalkyl;
where the alkyl groups in the definition of R3 are optionally substituted with xe2x80x94S(O)m(C1-C6)alkyl, xe2x80x94C(O)OX3, 1, 2, 3, 4 or 5 halogens, or 1, 2 or 3 OX3; X1 is O, S(O)m, xe2x80x94N(X2)C(O)xe2x80x94, xe2x80x94C(O)N(X2)xe2x80x94, xe2x80x94OC(O)xe2x80x94, xe2x80x94C(O)Oxe2x80x94, xe2x80x94CX2xe2x95x90CX2xe2x80x94, xe2x80x94N(X2)C(O)Oxe2x80x94, xe2x80x94OC(O)N(X2)xe2x80x94 or xe2x80x94Cxe2x89xa1Cxe2x80x94;
R4 is hydrogen, (C1-C6)alkyl or (C3-C7)cycloalkyl, or R4 is taken together with R3 and the carbon atom to which they are attached and form (C5-C7)cycloalkyl, (C5-C7)cycloalkenyl, a partially saturated or fully saturated 4- to 8-membered ring having 1 to 4 heteroatoms independently selected from the group consisting of oxygen, sulfur and nitrogen, or is a bicyclic ring system consisting of a partially saturated or fully saturated 5- or 6-membered ring, fused to a partially saturated, fully unsaturated or fully saturated 5- or 6-membered ring, optionally having 1 to 4 heteroatoms independently selected from the group consisting of nitrogen, sulfur and oxygen;
X4 is hydrogen or (C1-C6)alkyl or X4 is taken together with R4 and the nitrogen atom to which X4 is attached and the carbon atom to which R4 is attached and form a five to seven membered ring;
R6 is a bond or is 
where a and b are independently 0, 1, 2 or 3;
X5 and X5a are each independently selected from the group consisting of hydrogen, trifluoromethyl, A1 and optionally substituted (C1-C6)alkyl; the optionally substituted (C1-C6)alkyl in the definition of X5 and X5a is optionally substituted with a substituent selected from the group consisting of A1, OX2, xe2x80x94S(O)m(C1-C6)alkyl, xe2x80x94C(O)OX2, (C3-C7)cycloalkyl, xe2x80x94N(X2)(X2) and xe2x80x94C(O)N(X2)(X2);
or the carbon bearing X5 or X5a forms one or two alkylene bridges with the nitrogen atom bearing R7 and R8 wherein each alkylene bridge contains 1 to 5 carbon atoms, provided that when one alkylene bridge is formed then X5 or X5a but not both may be on the carbon atom and R7 or R8 but not both may be on the nitrogen atom and further provided that when two alkylene bridges are formed then X5 and X5a cannot be on the carbon atom and R7 and R8 cannot be on the nitrogen atom;
or X5 is taken together with X5a and the carbon atom to which they are attached and form a partially saturated or fully saturated 3- to 7-membered ring, or a partially saturated or fully saturated 4- to 8-membered ring having 1 to 4 heteroatoms independently selected from the group consisting of oxygen, sulfur and nitrogen;
or X5 is taken together with X5a and the carbon atom to which they are attached and form a bicyclic ring system consisting of a partially saturated or fully saturated 5- or 6-membered ring, optionally having 1 or 2 heteroatoms independently selected from the group consisting of nitrogen, sulfur and oxygen, fused to a partially saturated, fully saturated or fully unsaturated 5- or 6-membered ring, optionally having 1 to 4 heteroatoms independently selected from the group consisting of nitrogen, sulfur and oxygen;
Z1 is a bond, O or Nxe2x80x94X2, provided that when a and b are both 0 then Z1 is not Nxe2x80x94X2 or O;
R7 and R8 are independently hydrogen or optionally substituted (C1-C6)alkyl;
where the optionally substituted (C1-C6)alkyl in the definition of R7 and R8 is optionally independently,substituted with A1, xe2x80x94C(O)Oxe2x80x94(C1-C6)alkyl, xe2x80x94S(O)m(C1-C6)alkyl, 1 to 5 halogens, 1 to 3 hydroxy, 1 to 3 xe2x80x94Oxe2x80x94C(O)(C1-C10)alkyl or 1 to 3 (C1-C6)alkoxy; or
R7 and R8 can be taken together to form xe2x80x94(CH2)rxe2x80x94Lxe2x80x94(CH2)rxe2x80x94;
where L is C(X2)(X2), S(O)m or N(X2);
A1 for each occurrence is independently (C5-C7)cycloalkenyl, phenyl or a partially saturated, fully saturated or fully unsaturated 4- to 8-membered ring optionally having 1 to 4 heteroatoms independently selected from the group consisting of oxygen, sulfur and nitrogen, a bicyclic ring system consisting of a partially saturated, fully unsaturated or fully saturated 5- or 6-membered ring, optionally having 1 to 4 heteroatoms independently selected from the group consisting of nitrogen, sulfur and oxygen, fused to a partially saturated, fully saturated or fully unsaturated 5- or 6-membered ring, optionally having 1 to 4 heteroatoms independently selected from the group consisting of nitrogen, sulfur and oxygen;
A1 for each occurrence is independently optionally substituted, in one or optionally both rings if A1 is a bicyclic ring system, with up to three substituents, each substituent independently selected from the group consisting of F, Cl, Br, I, OCF3, OCF2H, CF3, CH3, OCH3, xe2x80x94OX6, xe2x80x94C(O)N(X6)(X6), xe2x80x94((O)OX6, oxo, (C1-C6)alkyl, nitro, cyano, benzyl, xe2x80x94S(O)m(C1-C6)alkyl, 1H-tetrazol-5-yl, phenyl, phenoxy, phenylalkyloxy, halophenyl, methylenedioxy, xe2x80x94N(X6)(X6), xe2x80x94N(X6)C(O)(X6), xe2x80x94SO2N(X6)(X6), xe2x80x94N(X6)SO2-phenyl, xe2x80x94N(X6)SO2X6, xe2x80x94CONX11X12, xe2x80x94SO2NX11X12, xe2x80x94NX6SO2X12, xe2x80x94NX6CONX11X12, xe2x80x94NX6SO2N11X12, imidazolyl, thiazolyl and tetrazolyl, provided that if A1 is optionally substituted with methylenedioxy then it can only be substituted with one methylenedioxy;
where X11 is hydrogen or optionally substituted (C1-C6)alkyl;
the optionally substituted (C1-C6)alkyl defined for X11 is optionally independently substituted with phenyl, phenoxy, (C1-C6)alkoxycarbonyl, xe2x80x94S(O)m(C1-C6)alkyl, 1 to 5 halogens, 1 to 3 hydroxy, 1 to 3 (C1-C10)alkanoyloxy or 1 to 3 (C1-C6)alkoxy;
X12 is hydrogen, (C1-C6)alkyl, phenyl, thiazolyl, imidazolyl, furyl or thienyl, provided that when X12 is not hydrogen, X12 is optionally substituted with one to three substituents independently selected from the group consisting of Cl, F, CH3, OCH3, OCF3 and CF3;
or X11 and X12 are taken together to form xe2x80x94(CH2)rxe2x80x94L1xe2x80x94(CH2)rxe2x80x94;
where L1 is C(X2)(X2), O, S(O)m or N(X2);
r for each occurrence is independently 1, 2 or 3;
X2 for each occurrence is independently hydrogen, optionally substituted (C1-C6)alkyl, or optionally substituted (C3-C7)cycloalkyl, where the optionally substituted (C1-C6)alkyl and optionally substituted (C3-C7)cycloalkyl in the definition of X2 are optionally independently substituted with xe2x80x94S(O)m(C1-C6)alkyl, xe2x80x94C(O)OX3, 1 to 5 halogens or 1-3 OX3;
X3 for each occurrence is independently hydrogen or (C1-C6)alkyl;
X6 is independently hydrogen, optionally substituted (C1-C6)alkyl, (C2-C6)halogenated alkyl, optionally substituted (C3-C7)cycloalkyl, (C3-C7)-halogenatedcycloalkyl, where optionally substituted (C1-C6)alkyl and optionally substituted (C3-C7)cycloalkyl in the definition of X6 is optionally independently substituted by 1 or 2 (C1-C4)alkyl, hydroxyl, (C1-C4)alkoxy, carboxyl, CONH2, xe2x80x94S(O)m(C1-C6)alkyl, carboxylate (C1-C4)alkyl ester, or 1H-tetrazol-5-yl; or
when there are two X6 groups on one atom and both X6 are independently (C1-C6)alkyl, the two (C1-C6)alkyl groups may be optionally joined and, together with the atom to which the two X6 groups are attached, form a 4- to 9-membered ring optionally having oxygen, sulfur or NX7;
X7 is hydrogen or (C1-C6)alkyl optionally substituted with hydroxyl; and
m for each occurrence is independently 0, 1 or 2;
with the proviso that:
X6 and X12 cannot be hydrogen when it is attached to C(O) or SO2 in the form C(O)X6, C(O)X12, SO2X6 or SO2X12; and
when R6 is a bond then L is N(X2) and each r in the definition xe2x80x94(CH2)rxe2x80x94Lxe2x80x94(CH2)rxe2x80x94 is independently 2 or 3.
In one aspect, this invention provides a method for treating insulin resistance in a mammal which comprises administering to said mammal an effective amount of a compound of formula I, as defined above, or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof.
A preferred method of the foregoing method is where the condition associated with insulin resistance is type I diabetes, type II diabetes, hyperglycemia, impaired glucose tolerance or an insulin resistant syndrome or state.
Another preferred method of the foregoing method is where the condition associated with insulin resistance is associated with obesity or old age.
A preferred method of the foregoing method is where said compound of formula I is of the following formula 
or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof where
R1 is xe2x80x94CH2-phenyl, R2 is methyl and R3 is xe2x80x94(CH2)3-phenyl;
R1 is xe2x80x94CH2-phenyl, R2 is methyl and R3 is 3-indolyl-CH2xe2x80x94;
R1 is xe2x80x94CH2-phenyl, R2 is ethyl and R3 is 3-indolyl-CH2xe2x80x94;
R1 is xe2x80x94CH2-4-fluoro-phenyl, R2 methyl and R3 is 3-indolyl-CH2xe2x80x94;
R1 is xe2x80x94CH2-phenyl, R2 is methyl and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-phenyl;
R1 is xe2x80x94CH2-phenyl, R2 is ethyl and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-phenyl;
R1 is xe2x80x94CH2-phenyl, R2 is xe2x80x94CH2CF3 and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-phenyl;
R1 is xe2x80x94CH2-4-fluoro-phenyl, R2 is methyl and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-phenyl;
R1 is xe2x80x94CH2-phenyl, R2 is t-butyl and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-phenyl; or
R1 is xe2x80x94CH2-phenyl, R2 is methyl and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-3,4-di-fluoro-phenyl.
Another preferred method of the foregoing method is where said compound of formula I is of the formula 
or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof where
R2 is methyl; A1 is 2-pyridyl; and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-phenyl;
R2 is CH2CF3; A1 is 2-pyridyl; and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-3-chloro-phenyl;
R2 is CH2CF3; A1 is 2-pyridyl; and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-4-chloro-phenyl;
R2 is CH2CF3; A1 is 2-pyridyl; and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-2,4-di-chloro-phenyl;
R2 is CH2CF3; A1 is 2-pyridyl; and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-3-chloro-thiophene or
R2 is CH2CF3; A1 is 2-pyridyl; and R3 is xe2x80x94CH2xe2x80x94Oxe2x80x94CH2-2,4-di-fluorophenyl.
Yet another preferred method of the foregoing method is where said compound of formula I or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers or the pharmaceutically acceptable salts and prodrugs thereof is the 3a(R,S),1(R) diastereomeric mixture, the 3a(R),1(R) diastereomer or the 3a(S),1(R) diastereomer of a compound selected from the group consisting of
2-amino-N-[1-(3a-benzyl-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridine-5-carbonyl)-4-phenyl-butyl]-isobutyramide,
2-amino-N-[2-(3a-benzyl-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo-[4,3-c]pyridin-5-yl)-1-(1H-indol-3-ylmethyl)-2-oxo-ethyl]-isobutyramide,
2-amino-N-[2-(3a-benzyl-2-ethyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-1-(1H-indol-3-ylmethyl)-2-oxo-ethyl]-isobutyramide,
2-amino-N-[2-[3a-(4-fluoro-benzyl)-2-methyl-3oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-1-(1H-indol-3-ylmethyl)-2-oxo-ethyl]-isobutyramide,
2-amino-N-[2-(3a-benzyl-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-1-benzyloxymethyl-2-oxo-ethyl]-isobutyramide,
2-amino-N-[2-(3a-benzyl-2-ethyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-1-benzyloxymethyl-2-oxo-ethyl]-isobutyramide,
2-amino-N-{2-[3a-benzyl-3-oxo-2-(2,2,2-trifluoro-ethyl)-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-1-benzyloxymethyl-2-oxo-ethyl}-isobutyramide,
2-amino-N-{1-benzyloxymethyl-2-[3a-(4-fluoro-benzyl)-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-2-oxo-ethyl}-isobutyramide,
2-amino-N-[2-(3a-benzyl-2-tert-butyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-1-benzyloxymethyl-2-oxo-ethyl]-isobutyramide and
2-amino-N-[2-(3a-benzyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-1-benzyloxymethyl-2-oxo-ethyl]-isobutyramide.
A preferred method of the immediately foregoing method is where said compound of formula I is 2-amino-N-[2-(3a-(R)-benzyl-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo-[4,3-c]pyridin-5-yl)-1-(R)-benzyloxymethyl-2-oxo-ethyl]-isobutyramide L-tartaric acid salt.
Still another preferred method of the foregoing method is a method where said compound of formula I or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers or the pharmaceutically acceptable salts and prodrugs thereof is the 3a-(R,S),1-(R) diastereomeric mixture, the 3a-(R),1-(R) enantiomer or 3a-(S),1-(R) enantiomer of a compound selected from the group consisting of
2-amino-N-[1-benzyloxymethyl-2-(2-methyl-3-oxo-3a-pyridin-2-ylmethyl-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-2-oxo-ethyl]-2-methyl-propionamide;
2-amino-N-{1-(3-chloro-benzyloxymethyl)-2-oxo-2-[3-oxo-3a-pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-ethyl}-2-methyl-propionamide;
2-amino-N-{1-(4-chloro-benzyloxymethyl)-2-oxo-2-[3-oxo-3a-pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-ethyl}-2-methyl-propionamide;
2-amino-N-{1-(2,4-dichloro-benzyloxymethyl)-2-oxo-2-[3-oxo-3a-pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-ethyl}-2-methyl-propionamide;
2-amino-N-{1-(4-chloro-thiophen-2-ylmethoxymethyl)-2-oxo-2-[3-oxo-3a-pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-2,3,3a,4,5,7-hexahydro-pyrazolo[3,4-c]pyridin-6-yl]-ethyl}-2-methyl-propionamide; and
2-amino-N-{1-(2,4-difluoro-benzyloxymethyl)-2-oxo-2-[3-oxo-3a-pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl]-ethyl}-2-methyl-propionamide.
Even still another preferred method of the foregoing method additionally comprises administering to a mammal in need thereof a growth hormone releasing hormone or a functional analog thereof, which are prepared by methods known in the art and some examples of which are described in European Patent Publication No. EP 511 003.
In another aspect, this invention provides pharmaceutical compositions useful for treating insulin resistance in a mammal which comprises a pharmaceutically acceptable carrier and an effective amount of a compound of formula I, as shown above, or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof.
In still another aspect, this invention provides methods for increasing levels of endogenous growth hormone, which comprises administering to a human or other animal in need thereof effective amounts of a functional somatostatin antagonist and a compound of formula I, as shown above, or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof.
In yet another aspect, this invention provides methods of treating or preventing congestive heart failure, obesity or frailty associated with aging, which comprises administering to a mammal in need thereof effective amounts of a functional somatostatin antagonist and a compound of formula I, as shown above, or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof. Preferred of the immediately foregoing method is where said functional somatostatin antagonist is an alpha-2 adrenergic agonist. Preferred of the immediately foregoing method is where said alpha-2 adrenergic agonist is selected from the group consisting of clonidine, xylazine and medetomidine. Preferred of the immediately foregoing method is where said compound of formula I is 2-amino-N-[2-(3a-(R)-benzyl-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo-[4,3-c]pyridin-5-yl)-1-(R)-benzyloxymethyl-2-oxo-ethyl]-isobutyramide L-tartaric acid salt.
This invention is also directed to pharmaceutical compositions which comprise a pharmaceutically acceptable carrier, an amount of an alpha-2 adrenergic agonist and an amount of a compound of formula I, as defined above, or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof.
This invention is further directed to methods of treating insulin resistance in a mammal which comprise administering to a mammal in need thereof an effective amount of a growth hormone releasing peptide or a growth hormone releasing peptide mimetic or a pharmaceutically acceptable salt thereof.
In one aspect, this invention is directed to the processes described below, where the xe2x80x9c*xe2x80x9d indicates stereochemical centers.
A process for the preparation of the compound of formula k, 
which comprises reacting the compound of formula g, 
with the compound of formula j, 
where Prt is an amine protecting group, in the presence of an organic base, a peptide coupling reagent, and a reaction inert solvent at a temperature between about xe2x88x9278xc2x0 C. to about xe2x88x9220xc2x0 C. to yield the compound of formula k.
Preferred of the foregoing process is where the peptide coupling reagent is 1-propane phosphonic acid cyclic anhydride and the compound of formula g has the R-configuration, the compound of formula j has the R-configuration and the compound of formula k has the 3a-(R),1-(R) configuration.
A process for the preparation of the compound of formula Z, 
which comprises reacting the compound of formula g, 
with the compound of formula j, 
in the presence of an organic base, a peptide coupling reagent, and a reaction inert solvent at a temperature between about xe2x88x9278xc2x0 C. to about xe2x88x9220xc2x0 C. to yield the compound of formula k, 
deprotecting the compound of formula k to yield the compound of formula I, 
reacting the compound of formula I with L-tartaric acid in an alcoholic solvent to yield the compound of formula Z.
Preferred of the immediately foregoing process is where the peptide coupling reagent is 1-propane phosphonic acid cyclic anhydride and the compound of formula g has the R-configuration, the compound of formula j has the R-configuration and each of the compounds of formula k, I and Z has the 3a-(R),1-(R) configuration.
A process for the preparation of the compound of formula g, 
which comprises reacting the compound of formula f, 
with a base in an inert solvent at a temperature of about xe2x88x9250 to xe2x88x9210xc2x0 C. wherein the chirality of the benzyl group is maintained, to yield the compound of formula g.
A process for the preparation of the compound of formula c, 
which comprises reacting the compound of formula b, 
where Prt is an amine protecting group, with an inorganic or organic base and benzyl bromide in a reaction inert solvent to yield the compound of formula c.
A process for the preparation of the compound of formula f, 
which comprises reacting the compound of formula e, 
with L-tartaric acid in a reaction inert organic solvent.
This invention also provides the R,S-enantiomeric mixture, the R-enantiomer or the S-enantiomer of the compound of formula 
where Prt is hydrogen or an amine protecting group.
In general the compounds of formula I or the stereoisomeric mixtures, diastereomerically enriched, diastereomerically pure, enantiomerically enriched or enantiomerically pure isomers, or the pharmaceutically acceptable salts and prodrugs thereof, utilized in methods of the instant invention can be made by processes which include processes known in the chemical arts.
In the above structural formulae and throughout the instant application, the following terms have the indicated meanings unless expressly stated otherwise.
The alkyl groups are intended to include those alkyl groups of the designated length in either a straight or branched configuration which may optionally contain double or triple bonds. Exemplary of such alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tertiary butyl, pentyl, isopentyl, hexyl, isohexyl, allyl, ethynyl, propenyl, butadienyl, hexenyl and the like.
When the definition C0-alkyl occurs in the definition, it means a single covalent bond.
The alkoxy groups specified above are intended to include those alkoxy groups of the designated length in either a straight or branched configuration which may optionally contain double or triple bonds. Exemplary of such alkoxy groups are methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tertiary butoxy, pentoxy, isopentoxy, hexoxy, isohexoxy, allyloxy, 2-propynyloxy, isobutenyloxy, hexenyloxy and the like.
The term xe2x80x9chalogenxe2x80x9d or xe2x80x9chaloxe2x80x9d is intended to include the halogen atoms fluorine, chlorine, bromine and iodine.
The term xe2x80x9chalogenated alkylxe2x80x9d is intended to include an alkyl group as defined hereinabove substituted by one or more halogen atoms as defined hereinabove.
The term xe2x80x9chalogenated cycloalkylxe2x80x9d is intended to include a cycloalkyl group substituted by one or more halogen atoms as defined hereinabove.
The term xe2x80x9carylxe2x80x9d is intended to include phenyl and naphthyl and aromatic 5- and 6-membered rings with 1 to 4 heteroatoms or fused 5- or 6-membered bicyclic rings with 1 to 4 heteroatoms of nitrogen, sulfur or oxygen. Examples of such heterocyclic aromatic rings are pyridine, thiophene (also known as thienyl), furan, benzothiophene, tetrazole, indole, N-methylindole, dihydroindole, indazole, N-formylindole, benzimidazole, thiazole, pyrimidine, and thiadiazole.
The chemist of ordinary skill will recognize that certain combinations of heteroatom-containing substituents listed in this invention define compounds which will be less stable under physiological conditions (e.g., those containing acetal or aminal linkages). Accordingly, such compounds are less preferred.
The expression xe2x80x9cprodrugxe2x80x9d refers to compounds that are drug precursors, which following administration, release the drug in vivo via some chemical or physiological process (e.g., a prodrug on being brought to the physiological pH is converted to the desired drug form). Exemplery prodrugs upon cleavage release the corresponding free acid, and such hydrolyzable ester-forming residues of the compounds of this invention include but are not limited to carboxylic acid substituents (e.g., R1 is xe2x80x94(CH2)qC(O)2X6 where X6 is hydrogen, or R2 or A1 contains carboxylic acid) wherein the free hydrogen is replaced by (C1-C4)alkyl, (C2-C12)alkanoyloxymethyl, (C4-C9)1-(alkanoyloxy)ethyl, 1-methyl-1-(alkanoyloxy)-ethyl having from 5 to 10 carbon atoms, alkoxycarbonyl-oxymethyl having from 3 to 6 carbon atoms, 1-(alkoxycarbonyloxy)ethyl having from 4 to 7 carbon atoms, 1-methyl-1-(alkoxycarbonyloxy)ethyl having from 5 to 8 carbon atoms, N-(alkoxycarbonyl)aminomethyl having from 3 to 9 carbon atoms, 1-(N-(alkoxycarbonyl)amino)ethyl having from 4 to 10 carbon atoms, 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, di-N,Nxe2x80x94(C1-C2)alkylamino(C2-C3)alkyl (such as xcex2-dimethylaminoethyl), carbamoyl-(C1-C2)alkyl, N,N-di-(C1-C2)-alkylcarbamoyl-(C1-C2)alkyl and piperidino-, pyrrolidino- or morpholino(C2-C3)alkyl.
Other exemplary prodrugs release an alcohol of formula I wherein the free hydrogen of the hydroxyl substituent (e.g., R1 contains hydroxyl) is replaced by (C1-C6)alkanoyloxymethyl, 1-((C1-C6)alkanoyloxy)ethyl, 1-methyl-1-((C1-C6)alkanoyl-oxy)ethyl, (C1-C6)alkoxycarbonyloxymethyl, N-(C1-C6)alkoxy-carbonylamino-methyl, succinoyl, (C1-C6)alkanoyl, xcex1-amino(C1-C4)alkanoyl, arylacetyl and xcex1-aminoacyl, or xcex1-aminoacyl-xcex1-aminoacyl wherein said xcex1-aminoacyl moieties are independently any of the naturally occurring L-amino acids found in proteins, P(O)(OH)2, xe2x80x94P(O)(O(C1-C6)alkyl)2 or glycosyl (the radical resulting from detachment of the hydroxyl of the hemiacetal of a carbohydrate).
Prodrugs of compounds of formula I where a carboxyl group in a carboxylic acid of formula I is replaced by an ester may be prepared by combining the carboxylic acid with the appropriate alkyl halide in the presence of a base such as potassium carbonate in an inert solvent such as DMF at a temperature of about 0xc2x0 C. to 100xc2x0 C. for about 1 to about 24 hours. Alternatively, the acid is combined with the appropriate alcohol as solvent in the presence of a catalytic amount of acid such as concentrated sulfuric acid at a temperature of about 20xc2x0 C. to 120xc2x0 C., preferably at reflux, for about 1 hour to about 24 hours. Another method is the reaction of the acid in an inert solvent such as THF, with concomitant removal of the water being produced by physical (e.g., Dean Stark trap) or chemical (e.g., molecular sieves) means.
Prodrugs of compounds of formula I where an alcohol function has been derivatized as an ether may be prepared by combining the alcohol with the appropriate alkyl bromide or iodide in the presence of a base such as potassium carbonate in an inert solvent such as DMF at a temperature of about 0xc2x0 C. to 100xc2x0 C. for about 1 to about 24 hours. Alkanoylaminomethyl ethers may be obtained by reaction of the alcohol with a bis-(alkanoylamino)methane in the presence of a catalytic amount of acid in an inert solvent such as THF, according to a method described in U.S. Pat. No. 4,997,984. Alternatively, these compounds may be prepared by the methods described by Hoffman et al. in J. Org. Chem. 1994, 59, p. 3530.
Certain of the above defined terms may occur more than once in the above formula and upon such occurrence each term shall be defined independently of the other.
Throughout the specification and appendent claims the following abbreviations are used with the following meanings:
The compounds utilized in a method of the instant invention all have at least one asymmetric center as noted by the asterisk in the structural formula I, above. Additional asymmetric centers may be present on the molecule depending upon the nature of the various substituents on the molecule. Each such asymmetric center will produce two optical isomers and it is intended that all such optical isomers, as separated, pure or partially purified optical isomers, racemic mixtures or diastereomeric mixtures thereof, be included within the scope of the instant invention. In the case of the asymmetric center represented by the asterisk, it has been found that the absolute stereochemistry of the more active and, thus, more preferred isomer is shown in formula IA. This preferred absolute configuration also applies to formula I. 
With the R4 substituent as hydrogen, the spatial configuration of the asymmetric center corresponds to that in a D-amino acid. In most cases this is also designated an R-configuration although this will vary according to the values of R3 and R4 used in making R- or S-stereochemical assignments.
The compounds of formula I utilized in methods of the instant invention are generally isolated in the form of their pharmaceutically acceptable acid addition salts, such as the salts derived from using inorganic and organic acids. Examples of such acids are hydrochloric, nitric, sulfuric, phosphoric, formic, acetic, trifluoroacetic, propionic, maleic, succinic, D-tartaric, L-tartaric, malonic, methane sulfonic and the like. In addition, certain compounds containing an acidic function such as a carboxy can be isolated in the form of their inorganic salt in which the counter-ion can be selected from sodium, potassium, lithium, calcium, magnesium and the like, as well as from organic bases.
The pharmaceutically acceptable salts are formed by taking about 1 equivalent of a compound of formula I and contacting it with about 1 equivalent of the appropriate corresponding acid of the salt which is desired. Work-up and isolation of the resulting salt is well-known to those of ordinary skill in the art.
The present invention includes within its scope pharmaceutical compositions comprising, as an active ingredient, an insulin resistance treating amount of at least one of the compounds of formula I in association with a pharmaceutically acceptable carrier. Further, the present invention includes within its scope pharmaceutical compositions comprising, as an active ingredient, at least one alpha-2 adrenergic agonist and at least one of the compounds of formula I in association with a pharmaceutically acceptable carrier. Optionally, the pharmaceutical compositions can further comprise an anabolic agent in addition to at least one of the compounds of formula I or another compound which exhibits a different activity, e.g., an antibiotic growth permittant or with other pharmaceutically active materials wherein the combination enhances efficacy and minimizes side effects.
Assay for Stimulation of GH Release From Rat Pituicytes
Compounds that have the ability to stimulate GH secretion from cultured rat pituitary cells are identified using the following protocol. This test is also useful for comparison to standards to determine dosage levels. Cells are isolated from pituitaries of 6-week old male Wistar rats. Following decapitation, the anterior pituitary lobes are removed into cold, sterile Hank""s balanced salt solution without calcium or magnesium (HBSS). Tissues are finely minced, then subjected to two cycles of mechanically assisted enzymatic dispersion using 10 U/mL bacterial protease (EC 3.4.24.4, Sigma P-6141, St. Louis, Mo.) in HBSS. The tissue-enzyme mixture is stirred in a spinner flask at 30 rpm in a 5% CO2 atmosphere at about 37xc2x0 C. for about 30 min., with manual trituration after about 15 min. and about 30 min. using a 10-mL pipet. This mixture is centrifuged at 200xc3x97g for about 5 min. Horse serum (35% final concentration) is added to the supernatant to neutralize excess protease. The pellet is resuspended in fresh protease (10 U/mL), stirred for about 30 min. more under the previous conditions, and manually triturated, ultimately through a 23-gauge needle. Again, horse serum (35% final concentration) is added, then the cells from both digests are combined, pelleted (200xc3x97g for about 15 min.), resuspended in culture medium (Dulbecco""s Modified Eagle Medium (D-MEM) supplemented with 4.5 g/L glucose, 10% horse serum, 2.5% fetal bovine serum, 1% non-essential amino acids, 100 U/mL nystatin and 50 mg/mL gentamycin sulfate, Gibco, Grand Island, N.Y.) and counted. Cells are plated at 6.0-6.5xc3x97104 cells per cm2 in 48-well Costar(trademark) (Cambridge, Mass.) dishes and cultured for 34 days in culture medium.
Just prior to GH secretion assay, culture wells are rinsed twice with release medium, then equilibrated for about 30 minutes in release medium (D-MEM buffered with 25 mM Hepes, pH 7.4 and containing 0.5% bovine serum albumin at 37xc2x0 C.). Test compounds are dissolved in DMSO, then diluted into pre-warmed release medium. Assays are run in quadruplicate. The assay is initiated by adding 0.5 mL of release medium (with vehicle or test compound) to each culture well. Incubation is carried out at about 37xc2x0 C. for about 15 minutes, then terminated by removal of the release medium, which is centrifuged at 2000xc3x97g for about 15 minutes to remove cellular material. Rat growth hormone concentrations in the supernatants are determined by a standard radioimmunoassay protocol described below.
Measurement of Rat Growth Hormone
Rat growth hormone concentrations were determined by double antibody radioimmunoassay using a rat growth hormone reference preparation (NIDDK-rGH-RP-2) and rat growth hormone antiserum raised in monkey (NIDDK-anti-rGH-S-5) obtained from Dr. A. Parlow (Harbor-UCLA Medical Center, Torrence, Calif.). Additional rat growth hormone (1.5 U/mg, #G2414, Scripps Labs, San Diego, Calif.) is iodinated to a specific activity of approximately 30 xcexcCi/xcexcg by the chloramine T method for use as tracer. Immune complexes are obtained by adding goat antiserum to monkey IgG (ICN/Cappel, Aurora, Ohio) plus polyethylene glycol, MW 10,000-20,000 to a final concentration of 4.3%; recovery is accomplished by centrifugation. This assay has a working range of 0.08-2.5 xcexcg rat growth hormone per tube above basal levels.
Assay for Exogenously-stimulated Growth Hormone Release in the Rat After Intravenous Administration of Test Compounds
Twenty-one day old female Sprague-Dawley rats (Charles River Laboratory, Wilmington, Mass.) are allowed to acclimate to local vivarium conditions (24xc2x0 C., 12 hr light, 12 hr dark cycle) for approximately 1 week before compound testing. All rats are allowed access to water and a pelleted commercial diet (Agway Country Food, Syracuse N.Y.) ad libitum. The experiments are conducted in accordance with the NIH Guide for the Care and Use of Laboratory Animals.
On the day of the experiment, test compounds are dissolved in vehicle containing 1% ethanol, 1 mM acetic acid and 0.1% bovine serum albumin in saline. Each test is conducted in three rats. Rats are weighed and anesthetized via intraperitoneal injection of sodium pentobarbital (Nembutol(copyright), 50 mg/kg body weight). Fourteen minutes after anesthetic administration, a blood sample is taken by nicking the tip of the tail and allowing the blood to drip into a microcentrifuge tube (baseline blood sample, approximately 100 xcexcl). Fifteen minutes after anesthetic administration, test compound is delivered by intravenous injection into the tail vein, with a total injection volume of 1 mL/kg body weight. Additional blood samples are taken from the tail at 5, 10 and 15 minutes after compound administration. Blood samples are kept on ice until serum separation by centrifugation (1430xc3x97g for 10 minutes at 10xc2x0 C.). Serum is stored at xe2x88x9280xc2x0 C. until serum growth hormone determination by radioimmunoassay as described above.
Assessment of Exoqenously-stimulated Growth Hormone Release in the Dog After Oral Administration
On the day of dosing, the test compound is weighed out for the appropriate dose and dissolved in water. Doses are delivered at a volume of 0.5-3 mL/kg by gavage to 2-4 dogs for each dosing regimen. Blood samples (5 mL) are collected from the jugular vein by direct vena puncture pre-dose and at 0.17, 0.33, 0.5, 0.75, 1, 2, 4, 6, 8 and 24 hours post dose using 5 mL vacutainers containing lithium heparin. The prepared plasma is stored at xe2x88x9220xc2x0 C. until analysis.
Measurement of Canine Growth Hormone
Canine growth hormone concentrations are determined by a standard radioimmunoassay protocol using canine growth hormone (antigen for iodination and reference preparation AFP-1983B) and canine growth hormone antiserum raised in monkey (AFP-21452578) obtained from Dr. A. Parlow (Harbor-UCLA Medical Center, Torrence, Calif.). Tracer is produced by chloramine T-iodination of canine growth hormone to a specific activity of 20-40 xcexcCi/xcexcg. Immune complexes are obtained by adding goat antiserum to monkey IgG (ICN/Cappel, Aurora, Ohio) plus polyethylene glycol, MW 10,000-20,000 to a final concentration of 4.3%; recovery is accomplished by centrifugation. This assay has a working range of 0.08-2.5 xcexcg canine GH/tube.
Assessment of Canine Growth Hormone and Insulin-like Growth Factor-1 Levels in the Dog After Chronic Oral Administration
The dogs receive test compound daily for either 7 or 14 days. Each day of dosing, the test compound is weighed out for the appropriate dose and dissolved in water. Doses are delivered at a volume of 0.5-3 ml/kg by gavage to 5 dogs for each dosing regimen. Blood samples are collected at days 0, 3, 7, 10 and 14. Blood samples (5 ml) are obtained by direct venipuncture of the jugular vein at pre-dose, 0.17, 0.33, 0.5, 0.754, 1, 2, 3, 6, 8, 12 and 24 hours post administration on days 0.7 and 14 using 5 ml vacutainers containing lithium heparin. In addition, blood is drawn pre-dose and 8 hours on days 3 and 10. The prepared plasma is stored at xe2x88x9220xc2x0 C. until analysis.
Female Rat Study
This study evaluates the effect of chronic treatment with a GHRP mimetic on weight, body composition and non-fasting plasma concentrations of glucose, insulin, lactate and lipids in estrogen-deficient and estrogen-replete female rats. Acute responsiveness of serum GH levels to i.v. administration of the GH releasing agent was assessed on the last day of dosing. Body weight was monitored weekly throughout the treatment period; additionally, body composition and plasma levels of glucose, insulin, lactate, cholesterol and triglycerides were assessed at the end of treatment.
Virgin female Sprague-Dawley rats were obtained from Charles River Laboratories (Wilmington, Mass.) and underwent bilateral ovariectomy (Ovx) or sham-surgery (Sham) at approximately 12 weeks of age. For sham surgeries, ovaries were exteriorized and replaced into the abdominal cavity. Following surgery the rats were housed individually in 20 cmxc3x9732 cmxc3x9720 cm cages under standard vivarium conditions (about 24xc2x0 C. with about 12 hours light/12 hours dark cycle). All rats were allowed free access to water and a pelleted commercial diet (Agway ProLab 3000, Agway Country Food, Inc., Syracuse, N.Y.). The experiment was conducted in accordance with NIH Guidelines for the Care and Use of Laboratory Animals.
Approximately seven months post-surgery, Sham and Ovx rats were weighed and randomly assigned to groups. Rats were dosed daily by oral gavage with 1 mL of either vehicle (1% ethanol in distilled-deionized water), 0.5 mg/kg or 5 mg/kg of a growth hormone releasing agent for 90 days. Rats were weighed at weekly intervals throughout the study. Twenty-four hours after the last oral dose, the acute response of serum growth hormone (GH) to test agent was assessed by the following procedure. Rats were anesthetized with sodium pentobarbital 50 mg/kg. Anesthetized rats were weighed and a baseline blood sample (xcx9c100 xcexcl) was collected from the tail vein. Test agent (growth hormone releasing agent or vehicle) was then administered intravenously via the tail vein in 1 mL. Approximately ten minutes after injection, a second 100 xcexcl blood sample was collected from the tail. Blood was allowed to clot at about 4xc2x0 C., then centrifuged at 2000xc3x97g for about 10 minutes. Serum was stored at about xe2x88x9270xc2x0 C. Serum growth hormone concentrations were determined by radioimmunoassay as previously described. Following this procedure, each anesthetized rat underwent whole body scanning by dual-energy X-ray absorptiometry (DEXA, Hologic QDR 1000/W, Waltham Mass.). A final blood sample was collected by cardiac puncture into heparinized tubes. Plasma was separated by centrifugation and stored frozen as described above.
Plasma insulin is determined by radioimmunoassay using a kit from Binax Corp. (Portland, Me.). The interassay coefficient of variation is xe2x96xa1 10%. Plasma triglycerides, total cholesterol, glucose and lactate levels are measured using Abbott VPTM and VP Super System(copyright) Autoanalyzer (Abbott Laboratories, Irving, Tex.), using the A-Gent(trademark) Triglycerides, Cholesterol and Glucose Test reagent systems, and a lactate kit from Sigma, respectively. The plasma insulin, triglycerides, total cholesterol and lactate lowering activity of a growth hormone releasing peptide (GHRP) or GHRP mimetic such as a compound of formula I, are determined by statistical analysis (unpaired t-test) with the vehicle-treated control group.
The compounds of formula I utilized in a method of this invention can be administered by oral, parenteral (e.g., intramuscular, intraperitoneal, intravenous or subcutaneous injection, or implant), nasal, vaginal, rectal, sublingual, or topical routes of administration and can be formulated with pharmaceutically acceptable carriers to provide dosage forms appropriate for each route of administration.
Solid dosage forms for oral administration include capsules, tablets, pills, powders and granules. In such solid dosage forms, the active compound is admixed with at least one inert pharmaceutically acceptable carrier such as sucrose, lactose, or starch. Such dosage forms can also comprise, as is normal practice, additional substances other than such inert diluents, e.g., lubricating agents such as magnesium stearate. In the case of capsules, tablets and pills, the dosage forms may also comprise buffering agents. Tablets and pills can additionally be prepared with enteric coatings.
Liquid dosage forms for oral administration include pharmaceutically acceptable emulsions, solutions, suspensions, syrups, the elixirs containing inert diluents commonly used in the art, such as water. Besides such inert diluents, compositions can also include adjuvants, such as wetting agents, emulsifying and suspending agents, and sweetening, flavoring and perfuming agents.
Preparations according to this invention for parenteral administration include sterile aqueous or non-aqueous solutions, suspensions, or emulsions. Examples of non-aqueous solvents or vehicles are propylene glycol, polyethylene glycol, vegetable oils, such as olive oil and corn oil, gelatin, and injectable organic esters such as ethyl oleate. Such dosage forms may also contain adjuvants such as preserving, wetting, emulsifying, and dispersing agents. They may be sterilized by, for example, filtration through a bacteria-retaining filter, by incorporating sterilizing agents into the compositions, by irradiating the compositions, or by heating the compositions. They can also be manufactured in the form of sterile solid compositions which can be dissolved in sterile water, or some other sterile injectable medium immediately before use.
Compositions for rectal or vaginal administration are preferably suppositories which may contain, in addition to the active substance, excipients such as coca butter or a suppository wax.
Compositions for nasal or sublingual administration are also prepared with standard excipients well known in the art.
The dosage of active ingredient in the compositions of this invention may be varied; however, it is necessary that the amount of the active ingredient be such that a suitable dosage form is obtained. The selected dosage depends upon the desired therapeutic effect, on the route of administration, and on the duration of the treatment. Generally, dosage levels of between 0.0001 to 100 mg/kg of body weight daily are administered to humans and other animals, e.g., mammals, to obtain effective release of growth hormone.
A preferred dosage range in humans is 0.01 to 5.0 mg/kg of body weight daily which can be administered as a single dose or divided into multiple doses.
A preferred dosage range in animals other than humans is 0.01 to 10.0 mg/kg of body weight daily which can be administered as a single dose or divided into multiple doses. A more preferred dosage range in animals other than humans is 0.1 to 5 mg/kg of body weight daily which can be administered as a single dose or divided into multiple doses.
The preparation of the compounds of formula I utilized in a method of the present invention can be carried out in sequential or convergent synthetic routes. Syntheses detailing the preparation of the compounds of formula I in a sequential manner are presented in the reaction schemes shown hereinbelow.
Many protected amino acid derivatives are commercially available, where the protecting groups Prt, Z100 and Z200 are, for example, BOC, CBZ, benzyl, ethoxycarbonyl groups, CF3C(O)xe2x80x94, FMOC, TROC, trityl or tosyl. Other protected amino acid derivatives can be prepared by literature methods. Some 3-oxo-2-carboxyl pyrrolidines, and 4-oxo-3-carboxyl piperidines are commercially available, and many other related pyrrolidines and 4-substituted piperidines are known in the literature.
Many of the schemes illustrated below describe compounds which contain protecting groups Prt, Z100 or Z200. Benzyloxycarbonyl groups can be removed by a number of methods including, catalytic hydrogenation with hydrogen in the presence of a palladium or platinum catalyst in a protic solvent such as methanol. Preferred catalysts are palladium hydroxide on carbon or palladium on carbon. Hydrogen pressures from 1-1000 psi may be employed; pressures from 10 to 70 psi are preferred. Alternatively, the benzyloxycarbonyl group can be removed by transfer hydrogenation.
Removal of BOC protecting groups can be carried out using a strong acid such as trifluoroacetic acid or hydrochloric acid with or without the presence of a cosolvent such as dichloromethane, ethyl acetate, ether or methanol at a temperature of about xe2x88x9230 to 70xc2x0 C., preferably about xe2x88x925 to about 35xc2x0 C.
Benzyl esters of amines can be removed by a number of methods including, catalytic hydrogenation with hydrogen in the presence of a palladium catalyst in a protic solvent such as methanol. Hydrogen pressures from 1-1000 psi may be employed; pressures from 10 to 70 psi are preferred. The addition and removal of these and other protecting groups are discussed by T. Greene in Protective Groups in Organic Synthesis, John Wiley and Sons, New York, 1981. 
SCHEME 1: The protected amino acid derivatives 1 are in many cases commercially available, where the protecting group Prt is, for example, BOC, FMOC or CBZ groups. Other amino acids can be prepared by literature methods.
As illustrated in Scheme 1, coupling of amines of formula 2 with protected amino acids of formula 1, where Prt is a suitable protecting group, is conveniently carried out in an inert solvent such as dichloromethane or DMF by a coupling reagent such as EDC or DCC in the presence of HOBT or HOAT. In the case where the amine is present as the hydrochloride salt, it is preferable to add one or two equivalents of a suitable base such as triethylamine to the reaction mixture. Alternatively, the coupling can be effected with a coupling reagent such as BOP in an inert solvent such as methanol. Such coupling reactions are generally conducted at temperatures of about xe2x88x9230xc2x0 to about 80xc2x0 C., preferably xe2x88x9210xc2x0 to about 25xc2x0 C. For a discussion of other conditions used for coupling peptides see Houben-Weyl, Vol. XV, part II, E. Wunsch, Ed., George Theime Verlag, 1974, Stuttgart. Separation of unwanted side products and purification of intermediates is achieved by chromatography on silica gel, employing flash chromatography (W. C. Still, M. Kahn and A. Mitra, J. Org. Chem. 43 2923 1978), by crystallization or by trituration.
Transformation of the compound of formula 3 into intermediates of formula 4 can be carried out by removal of the protecting group Prt as described above. Coupling of intermediates of formula 4 to amino acids of formula 5 can be effected as described above to give intermediates of formula 6. Deprotection of the amine 6 affords compounds of formula 7. 
SCHEME 2: Alternatively, compounds of formula 7 can be prepared by a convergent route as shown in Scheme 2. Intermediate esters of formula 8 can be prepared by treating amino acids 1, where Prt is a suitable protecting group, with a base such as potassium carbonate followed by an alkyl halide such as iodomethane in a suitable solvent such as DMF. Deprotection of the amine transforms 8 into 9. Alternatively, many amino acids of formula 9 are commercially available. Intermediate 10 is generated by coupling 9 to amino acid 5. The ester of intermediate 10 can be converted to intermediate acid 11 by a number of methods known in the art; for example, methyl and ethyl esters can be hydrolyzed with lithium hydroxide in a protic solvent such as aqueous methanol or aqueous THF at a temperature of about xe2x88x9220xc2x0 to 120xc2x0 C., preferably about 0xc2x0 to 50xc2x0 C. In addition, removal of a benzyl group can be accomplished by a number of reductive methods including hydrogenation in the presence of platinum or palladium catalyst in a protic solvent such as methanol. Acid 11 can then be coupled to amine 2 to give intermediates of formula 6. Transformation of 6 to 7 can be achieved by removal of the protecting group Z200. 
SCHEME 3: The esters of formula 6 can be converted to intermediate acids of formula 13 by a number of methods known in the art; for example, methyl and ethyl esters can be hydrolyzed with lithium hydroxide in a protic solvent such as aqueous methanol or aqueous THF at a temperature of about xe2x88x92200 to 120xc2x0 C., preferably about 0xc2x0 to 50xc2x0 C. In addition, removal of a benzyl group can be accomplished by a number of reductive methods including hydrogenation in the presence of platinum or palladium catalyst in a protic solvent such as methanol. Coupling the acid 13 to amine 16 generates the intermediates of formula 14. Transformation of 14 to 15 can be achieved by removal of the protecting group Z. 
SCHEME 4: Esters of formula 17 can be prepared by treating an acid of formula 5 with hydroxysuccinimide in the presence of a coupling agent such as EDC in an inert solvent such as methylene chloride as illustrated in Scheme 4. Treatment of an ester 17 with an amino acid of formula 1 in a solvent such as dioxane, THF or DMF in the presence of a base such as diisopropylethylamine produces 11. 
SCHEME 5: As illustrated in Scheme 5, alkylation of the diphenyloxazinone of formula 18 with cinnamyl bromide in the presence of sodium bis(trimethylsilyl)amide generates 19 which is then converted to the desired (D)-2-amino-5-phenylpentanoic acid 20 by removing the protecting group (Prt) and hydrogenation over a PdCl2 catalyst. 
SCHEME 6: Treatment of an ester of formula 21 with a base such as sodium hydride in a solvent such as DMF followed by an alkyl halide 22 generates a compound of formula 23 as illustrated in Scheme 6. Treating a compound of formula 23 with a hydrazine of formula 24 such as hydrazine or methyl-hydrazine in a solvent such as refluxing ethanol, followed by concentration and heating the residue in toluene at temperatures at or near reflux results in a compound of formula 25. Alternatively, 23 can be treated with a salt of a hydrazine in the presence of sodium acetate in ethanol to give 25. Deprotection of the amine generates a compound of formula 28. Thioamides of formula 26 can be formed by treating 25 with Lawesson""s reaagent in refluxing toluene or benzene. Removal of the protecting group transforms 26 into 27. 
SCHEME 7: Treatment of a compound of formula 21 with a hydrazine of formula 24 in a solvent such as refluxing ethanol, followed by concentration and heating the residue in toluene at temperatures at or near reflux results in compounds of formula 29. Alternatively, 21 can be treated with a salt of a hydrazine in the presence of sodium acetate in refluxing ethanol to give 29. The amide of formula 29 can be treated with a base such as sodium hydride in a solvent such as DMF followed by an alkyl halide to give 25. Deprotection of the amine generates a compound of formula 28. 
SCHEME 8: Reaction of a ketoester of formula 30 with a chiral amine such as alpha-methylbenzylamine with a suitable aldehyde such as formaldehyde, or reaction of a vinyl ketoester of formula 31 with a chiral amine such as alpha-methylbenzylamine with a suitable aldehyde such as formaldehyde, affords a compound of formula 32 via a double Mannich reaction. Reaction of 32 with a hydrazine generates a chiral compound of formula 33. Deprotection of the nitrogen with hydrogen and a suitable catalyst such as palladium affords compounds of formula 34. 
SCHEME 9: Treatment of a compound of formula 81 with a reducing agent such as sodium borohydride and protection of the nitrogen affords a compound of formula 82. Protection of the alcohol affords 83. Saponification of the ester affords a compound of formula 84. Reaction of 84 with thionyl chloride followed by treatment with diazomethane affords the homologated acid of formula 85. Esterification of 85 affords a compound of formula 86, which is O-deprotected to give 87. Oxidation of 87 affords a ketone of formula 88. Reaction of 88 with a hydrazine, followed by nitrogen deprotection affords a compound of formula 44. 
SCHEME 10: Treatment of a compound of formula 35 with a base such as sodium hydride in a solvent such as DMF followed by treatment with diethylcarbonate generates the ethyl ester of compound 36. Deprotection of the amine transforms 36 into 37. 
SCHEME 11: Treatment of a malonic ester of formula 38 with a base such as sodium hydride in a solvent such as DMF and subsequent hydrogenolysis of the benzyl group with hydrogen and a catalyst such as palladium in a suitable solvent such as methanol produces the ester of formula 39. Deprotection of the amine generates compounds of formula 40. 
SCHEME 12: Treatment of a ketone of formula 41 with a secondary amine such as piperidine in a suitable solvent such as benzene with removal of water affords an enamine of formula 42. Alkylation of the enamine with an alpha-haloester such as ethylbromoacetate in a suitable solvent such as benzene or THF using a suitable base such as LDA or NaN(SiMe3)2 affords a ketoester of formula 43. Reaction with a hydrazine of formula 24 affords the compound of formula 44. Deprotection of the nitrogen affords compounds of formula 45. 
SCHEME 13: Treatment of a ketoester of formula 37 with an iodonium salt such as diphenyliodonium trifluoroacetate in a suitable solvent such as t-butanol generates a ketoester of formula 46. Reaction of 46 with a hydrazine generates a compound of formula 47. Deprotection of the nitrogen affords compounds of formula 48, see Synthesis, (9), 1984 p. 709 for a detailed description. 
SCHEME 14: Treatment of a ketoester of formula 37 with an olefin such as acrylonitrile generates a ketoester of formula 49. Reaction of 49 with a hydrazine generates a compound of formula 50. Deprotection of the nitrogen affords compounds of formula 51. 
SCHEME 15: Treatment of a ketoester of formula 37 with allyl bromide and a suitable base such as sodium hydride in a suitable solvent such as DMF affords a ketoester of formula 52. Reaction of 52 with a hydrazine generates a compound of formula 53. Ozonolysis of 53 in a suitable solvent such as methylene chloride followed by treatment with a reducing agent such as dimethylsulfide affords an aldehyde of formula 54. Oxidation of 54 affords a carboxylic acid of formula 55. Curtius rearrangement of 55, followed by hydrolysis of the intermediate isocyanate affords a primary amine of formula 56. Treatment of a compound of formula 56 with an isocyanate or carbamate affords a urea of formula 57. Deprotection of the nitrogen affords compounds of formula 58. 
SCHEME 16: Treatment of a compound of formula 54 with a primary amine affords an imine of formula 59. Reduction of a compound of formula 59 affords a compound of formula 60. Treatment of a compound of formula 60 with an acylating agent affords a compound of formula 61. Deprotection of the nitrogen affords compounds of formula 62. 
SCHEME 17: Treatment of a compound of formula 54 with a reducing agent such as sodium borohydride affords a compound of formula 63. Reaction of 63 with an acylating agent such as an isocyanate or carbamate affords compounds of formula 64. Deprotection of the nitrogen affords compounds of formula 65. 
SCHEME 18: Treatment of a compound of formula 63 with a phosphine such as triphenyl phosphine and an azo compound such as diethylazodicarboxylate and an oxindole affords a compound of formula 66. Deprotection of the nitrogen affords the compound of formula 67. 
SCHEME 19: Treatment of a ketoester of formula 37 with a chiral diol and acid catalyst with removal of water in a suitable solvent such as benzene affords a chiral ketal of formula 68. Alkylation of 68 with an alkyl halide in the presence of a base such as LDA followed by acid-catalyzed hydrolysis of the ketal affords chiral ketoesters of formula 69. Reaction of 69 with a hydrazine generates chiral compounds of formula 70. Deprotection of the nitrogen affords compounds of formula 71. 
SCHEME 20: Treatment of a ketoester of formula 37 with a chiral amino acid ester such as valine t-butyl ester affords a chiral enamine of formula 72. Alkylation of 72 with an alkyl halide in the presence of a base such as LDA followed by acid-catalyzed hydrolysis of the enamine affords chiral ketoesters of formula 69. Reaction of 69 with a hydrazine generates chiral compounds of formula 70. Deprotection of the nitrogen affords compounds of formula 71. 
SCHEME 21: Deprotection of the nitrogen of 25 affords compounds of formula 28. Salt formation of 28 with a chiral acid affords a mixture of diastereomeric salts of formula 73. Crystallization of the diastereomeric salts affords the acid salt of chiral compounds of formula 70. Decomposition of the salt 70 with base liberates chiral compounds of formula 71. 
SCHEME 22: Alkylation of compounds of formula 25 with an allylic acetate in the presence of a suitable catalyst such as palladium tetrakis(triphenylphdsphine) affords compounds of formula 74. Deprotection of the nitrogen affords compounds of formula 75, see Tetrahedron (50) p. 515, 1994 for a detailed discussion. 
SCHEME 23: Treatment of a ketodiester of formula 76 with an alkyl halide in the presence of a base such as sodium hydride followed by acid-catalyzed hydrolysis and decarboxylation, followed by esterification with methyliodide and a suitable base affords a compound of formula 77. Reaction of a compound of formula 77 with a suitable aldehyde such as formaldehyde and benzylamine affords a compound of formula 78. Reaction of a compound of formula 78 with a hydrazine generates chiral compounds of formula 79. Deprotection of the nitrogen affords compounds of formula 80. 
SCHEME 24: Treatment of an amine of formula 23 with an acid of formula 11 in an inert solvent such as dichloromethane or DMF by a coupling reagent such as EDC or DCC in the presence of HOBT affords compounds of formula 89. Reaction of compounds of formula 89 with a hydrazine generates compounds of formula 6. Deprotection of the nitrogen affords compounds of formula 7. 
SCHEME 25: Treatment of a hydroxyacetoacetate ester of formula 90 with an alkyl halide in the presence of a suitable base such as sodium hydride affords compounds of formula 91. Reaction of 91 with a hydrazine generates compounds of formula 92. O-Alkylation of the carbonyl oxygen of 92 affords 93 which is converted to the halide 94. Displacement of the halide X by cyanide ion affords the nitrile 95. Reduction of 95 gives the primary amine 96 which is deprotected and cyclized in the presence of formaldehyde to afford 28. 
SCHEME 26: Treatment of a beta-keto-protected aminovalerate such as 97 with an alkyl halide in the presence of a suitable base such as sodium hydride affords compounds of formula 98. Reaction of compounds of formula 98 with a hydrazine generates compounds of formula 99. Deprotection of compounds of formula 99 affords primary amines of formula 100. Cyclization of compounds of formula 100 in the presence of formaldehyde affords compounds of formula 28. 
SCHEME 27: Treatment of the amine of formula 23a with an acid such as 1 in the presence of EDC and HOAT in a suitable solvent provides keto-esters of formula 23b. The keto-ester 23b can be treated with a salt of hydrazine in the presence of sodium acetate in refluxing ethanol to give hydrazines of formula 23c. Deprotection under suitable conditions gives amines of formula 4. Coupling of intermediates of formula 4 to amino acids of formula 5 can be effected as described above to give intermediates of formula 6. Deprotection of amine 6 affords compounds of formula 7. 
SCHEME 28: Prt represents an amine protecting group that will be known to one skilled in the art. BOC has been used for Prt to illustrate the preferred protecting group but the use of BOC should not be taken as limiting the scope of this disclosure. Further, although the scheme illustrates the synthesis of the compound of formula m using particular isomers, other isomers and/or isomeric mixtures are also within the scope the instant disclosure.
Step A
To a solution of 4-oxo-piperidine-3-carboxylic acid ethyl ester hydrochloride in a reaction inert organic solvent such as IPE, THF, methylene chloride and EtOAc with or without water as a cosolvent, preferably IPE and water, is added an inorganic or organic base such as TEA, DMAP, an hydroxide or a carbonate, preferably TEA, followed by an amine protecting group, preferably (Boc)2O. The mixture is stirred for about 1-24 hours, preferably overnight, preferably under nitrogen. The organic phase is separated and worked-up according to standard procedures known to those skilled in the art, and concentrated to afford the desired product as crystals.
Step B
To a solution of 4-oxo-piperidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester in an organic solvent such as THF, IPE, an alcohol, DNF, or DMSO, preferably DMF, an inorganic or organic base such as TEA, DMAP, an hydroxide or a carbonate, preferably lithium carbonate, is added, followed by benzyl bromide. The mixture is heated to about 25-100xc2x0 C., preferably 60xc2x0 C., and stirred for about 1-24 hours, preferably 20 hours. The reaction mixture is then cooled to room temperature and extracted with an organic solvent such as IPE, toluene, THF or EtOAc and worked-up according to standard procedures known to those skilled in the art to yield the desired compound.
Step C
To a solution of 3-benzyl-4-oxo-piperidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester in an organic solvent such as an alcohol, THF or toluene is added methylhydrazine, followed by an acid such as sulfuric acid, HCl, AcOH or TsOH, preferably acetic acid at about 0xc2x0 C. to room temperature. The reaction mixture is heated slowly to about 40-100xc2x0 C., preferably about 65xc2x0 C. and stirred for about 3-10 hours, preferably about 7.5 hours. After cooling to room temperature, the organic layer is washed with 10% sodium bicarbonate and worked-up according to standard procedures known to those skilled in the art and concentrated to yield the desired compound.
Step D
The concentrated solution from step C is mixed with an organic solvent such as IPE, cooled to about xe2x88x9210-10xc2x0 C., preferably 0xc2x0 C., an acid such as MeSO3H, TFA or HCl, preferably HCl gas, is introduced repeatedly and stirred at room temperature until the hydrolysis is complete. The mixture is concentrated, an organic solvent such as methylene chloride, IPE or THF is added, followed by a base such as a hydroxide, a carbonate, preferably NH4OH. The mixture is then extracted with methylene chloride, IPE or THF and concentrated to yield the desired compound.
Step E
To a solution of 3a-benzyl-2-methyl-2,3a,4,5,6,7-hexahydro-pyrazolo[4,3-c]pyridin-3-one in a mixture of acetone/water (1% to 11% water, preferably 5% water in acetone) is added L-tartaric acid. The mixture is heated to 25-60xc2x0 C., preferably about 50xc2x0 C., and stirred, preferably overnight. The reaction mixture is cooled to preferably about 10-15xc2x0 C. and precipitates are filtered, washed with cold acetone/water and dried to yield the desired compound.
Step G
2-Aminoisobutyric acid, a base such as a hydroxide, preferably 1N NaOH, (Boc)2O and an organic solvent such as THF, IPE or dioxane are mixed together and stirred at room temperature overnight. The reaction mixture is diluted with organic solvent such as ethyl acetate and adjusted to about pH 3 to 7 by adding an aqueous acid such as HCl. The organic phase is separated and worked-up according to standard procedures known to those skilled in the art to yield the desired compound.
Step H
To a solution of 2-amino-3-benzyloxy-propionic acid in water and an inorganic or organic base, preferably TEA, is added 2-tert-butoxycarbonylamino-2-methyl-propionic acid 2,5-dioxo-pyrrolidin-1-yl ester in an organic solvent such as THF. The mixture is stirred preferably overnight at preferably room temperature, preferably under nitrogen. An aqueous acid such as 10% citric acid solution is added to the mixture. The mixture is stirred for several minutes, then diluted with an organic solvent such as ethyl acetate. The organic phase is separated from the mixture and worked-up according to standard procedures known to those skilled in the art and then concentrated to yield the desired compound.
Steps F and I
To a solution of 3a-(R)-benzyl-2-methyl-2,3a,4,5,6,7-hexahydro-pyrazolo[4,3-c]pyridin-3-one, L-tartrate in organic solvent such as ethyl acetate at about xe2x88x9278 to xe2x88x9220 xc2x0 C., preferably about xe2x88x9266xc2x0 C., is added a base such as TEA. The mixture is stirred for 1-24 hours, preferably about 1.5 hours. After removal of the precipitated salt, 3-benzyloxy-2-(2-tert-butoxycarbonylamino-2-methyl-propionylamino)-propionic acid and a base such as TEA are added at about xe2x88x9250 to 0xc2x0 C., preferably about xe2x88x9235xc2x0 C., followed by the addition of a peptide coupling reagent, preferably 50% 1-propane phosphonic acid cyclic anhydride (PPAA) in ethyl acetate. The mixture is stirred for about 1-6 hours, preferably about 2 hours at xe2x88x9250 to 0xc2x0 C., preferably about xe2x88x9220xc2x0 C. to about xe2x88x9227xc2x0 C., then the temperature was slowly raised to preferably about 0xc2x0 C. The reaction mixture is poured into water and extracted with an organic solvent such as IPE and the organic layer is separated and worked-up according to standard methods known to those skilled in the art to yield the desired compound.
Step J
To a solution of {1-[2-(3a-(R)-benzyl-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-1-(R)-benzyloxymethyl-2-oxo-ethylcarbamoyl]-1-methyl-ethyl}-carbamic acid tert-butyl ester in an organic solvent such as methylene chloride at about xe2x88x9210 to 10xc2x0 C., preferably about 0-5xc2x0 C. is added TFA, preferably the temperature is maintained below about 5xc2x0 C. The temperature is then raised to room temperature. The mixture is stirred for about 1-6 hours, preferably about 3 hours. Methylene chloride is replaced with another organic solvent such as ethyl acetate. The mixture is then adjusted to about pH 7 to pH 9, preferably pH 8, with an aqueous base such as saturated sodium bicarbonate solution and then worked-up according to standard methods known to those skilled in the art to yield the desired compound.
Step K
To a solution of 2-amino-N-[2-(3a-(R)-benzyl-2-methyl-3-oxo-2,3,3a,4,6,7-hexahydro-pyrazolo[4,3-c]pyridin-5-yl)-1-(R)-benzyloxymethyl-2-oxo-ethyl]-2-methyl-propionamide from step I in an alcohol such as methanol is added L-(+)-tartaric acid and the mixture is stirred overnight. The resulting solution is filtered and concentrated. An organic solvent such as IPE or ethyl acetate is added and the remaining alcohol is removed azeotropically. The solid that is isolated is dissolved in ethyl acetate and the solution is refluxed, then allowed to cool to room temperature to yield crystals of the desired product.